I was recently discussing whether or not you should directly test the functionality of private methods in a Go project. The other person reasoned for testing public and private functions to ensure 100% test coverage.

Testing private functions in Go is very simple. To do this you put your implementation and tests in the same package. The private functions are available in the test file as they are in the implementation file.

However just because you do not write tests that directly access the private functions, this does not mean you cannot achieve 100% code coverage. In fact if you follow Test Driven Development (TDD) most private functions will only be created during refactoring.

I prefer to only test public functions.

Lets go through a slightly contrived example.

We are going to implement a number package with two functions. One will add one integer to another. The second function will take one integer away from another. Both functions will return the result of the sum as the string representation of the number. i.e. result is 4, the value returned “four”.

We will only return a string for numbers between 0 and 10. If the number is out side of that range we will return “Cannot convert # to a string”.

Add Function

First we implement the functionality of the Add function. Testing and implementing for one simple addition with a result within our range and one addition with a result outside our range.

We now have two functions and all the tests are passing with 100% test coverage. So far so good. However we have some duplication, this can be removed with a small refactor.

refactor

We already have all the test we need. We just need to move the duplicate code to it own function. There is currently no need for its functionality to be accessed from outside of the number package so we make it a private function.

Now when we run the tests they all pass, so our refactor is good. We still have 100% test coverage without having to add new tests to cover our new private function intToString. The moved functionality is being indirectly tested by the existing tests on our public functions.

The completed implementation that ensure all some that result in a value between 0 and 10 can be be found in this Github repository.

I am currently working out how I can be a better team member. I think one of the key parts of a team member is to ensure you are helping all of your team to become better programmers. By helping them to find the answer when they are asking questions and reviewing there code when they submit pull requests to give constructive feedback.

At work we use Slack as one of our communication tools. Other than just talking to each other it is the main way we ask each other questions or announce that a pull request is ready for review. I have started to use the Highlight Words of Slack feature to alert me to when there are members of my team looking for help but not directly asking me a question.

The Highlight Words feature allows you to provide a comma separated list a set of key words and phrases that you want to be alerted to as if someone has used @here or @username in one of the channel.

This is the current list of words and phrases I use to get alerts when someone is looking for help.

not sure why, for some reason, don’t get it, dont get it, make sense, makes no sense, help, question

I also use the pattern below to setup alerts for pull request links being posted on slack. I use this pattern so I only receive alerts about repositories I am interested in.

/[organisation]/[repo]/pull

If you are going to use them make sure you setup alerts for highlighting words at the top of the page.

Using this also means that I spend less time reading through slack.

This setting can be different for each of the teams you are in. Setup can be done here.

Recently at work I had to create a PHP client library for one of our REST microservices. The client library will be used by many of our projects. I wanted to implement the library using test driven development

I had some trouble finding any advice or examples of client libraries that had be implemented using Test Driven Development where the tests did not actually rely on making calls the service.

I wanted Guzzle to be a dependency of the client library. Doing this would allow me to pass in a mocked Guzzle instance to my PHPSpec tests .This would mean my unit tests would not rely on communicating with API to pass.

However I did not want users of the client library to have to worry about the Guzzle dependency.

After a discussion with some colleagues I decided the best approach was have the client object require Guzzle as a constructor dependency but provide a static factory method for client library users to use for construction without providing the Guzzle dependency.

Any users of the client library now have a very simple way to instantiate the client library.

In this example the base URI is hard coded as the is only one version of the service. If you have different environments to work with you can pass URI or a constant for the environment in to the create() function.

Feature: Getting Pokemon
Scenario: Ensure that is it possible to find a Pokemon by its ID
Given The client has been instantiated
When I try to find a Pokemon by ID 1
Then I should have been returned a Pokemon

During the talk I mention that I used recruitment tests as a way to prove to myself that I can write good code and also as an extended code kata to improve my use of proper test driven development.

A number of people have expressed an interest in having a go at these tests themselves. I thought rather than emailing them out to people that were interested, I would make a little open source project out of it.

So I have created a GitHub repository containing a collection of the recruitment test that I have enjoyed implementing. I hope you enjoy the challenges as well.

If you have completed any fun or interesting recruitment test or you company have a good recruitment test it would be great if you could add to the project with a Pull Request. See the contribution if you do want to submit a test yourself.

I recently gave a ten minute talk about Imposter Syndrome at a Lightning Talk session organised at work. Here is the video of that talk.

I decided to give the talk because I had been suffering with Imposter Syndrome for quite some time and for a lot of that time I did not realise that other developers suffered with the same fears that I did.

I wanted to share my experiences with Imposter Syndrome.
Why it affected me?
How it affected me?
How I am attempting to get over it.
To let others that are suffering with Imposter Syndrome that it is not just them that feel like that and It is possible to get past it.

This is also the same talk I gave as a lightning talk PHP North West Conference.

I hope to extend this 10 minute lightning talk into a slightly longer talk. I am not sure it could stretch to a full hour conference slot, but I think I could get it to 30 minutes meetup talk. If anyone has a meetup they would like me to present this talk at please get in contact I would love to hear from you.

In my first post on Single Table Inheritance I had some example code that made use of a $tax variable to demonstrate where tax is added or removed. This simplification hides some complexity of the actual implementation.

In the actual implementation I needed to have access to a TaxCalculator object in all Price entities. The issue I had was how to ensure this happens without having to remember to manually inject the TaxCalculator everywhere Price entities are retrieved or persisted.

To do this I used a Doctrine feature called Entity Listeners. The Listener functionality allows you to access entities during a number of Doctrine operations. Once configured you are able to hook into a number of different events before or after various CRUD events, they are:

preFlush

postLoad

PrePersist

PostPersist

PreUpdate

PostUpdate

PostRemove

PreRemove

The listening function is passed the entity that triggering the event and an instance of Doctrine\Common\EventArgs. In my example i do not use the EventArgs object. It can be used to give you another way to access the entity triggering the event or an instance of Doctrine/ORM/EntityManager.

The following Doctrine YAML configuration specifies the Entity Event Listener class (Braddle\EntityListener) for the Price entities.

Here is the implementation of my Entity Event Listener (Braddle\EntityListener) this listener injects a TaxCalculator into price entities. I have only used the postLoad and postPersist functions so that i can ensure that new Prices have a TaxCalculator injected when they are saved and all existing Prices when they are retrieved from the database.

The Class Table Inheritance feature of Doctrine allows you to have a number of different entities similar to Single Table Inheritance. The difference with Class Table Inheritance is it allows you to split the data specific to an entity in to a separate table. This allows each entity to have extra data specific to its needs, without having a table with a large number of null-able columns.

When creating a new entity you simply instantiate the class for the specific type required. When you persist the entity Doctrine creates an entry in the base table with the discriminator of your chosen class, Doctrine will also create an entry in the class specific table with a foreign key linking back to the base table.

When retrieving a specific entity from the database Doctrine uses the discriminator to decide which class to construct the data with. Doctrine also loads any class specific data from the class specific table.

If I were implement an Order Item system using Class Table Inheritance, I would create an abstract class and base table that could handle all of the generic Order Item functionality and data. Creating a concrete implementations for each specific Order Items requirements.

In the example configuration I have only created two concrete implementations one for products and one for vouchers.

This implementation of the OrderItems maintains a clean database without any unecessary null-able columns. The implementation also conforms to the Single Responsibility Principle as a concrete OrderItem class only needs to be edited if the requirements of that specific type of OrderItem change. If I needed to create a new OrderItem for employee discount, I would create and configure a new EmployeeDiscountOrderItem entity in Doctrine without having to touch any existing OrderItem classes.

When creating an entity you simple construct the desired class. When you persist the new entity to your data store, Doctrine stores the discriminator (class type identifier) with the rest of the entity’s data.

When retrieving a specific entity from the database Doctrine uses a discriminator to decide which class to construct with the data.

I have recently used the single table inheritance feature to refactor a Price class that used to use a boolean field to determine if the price contained within the entity was inclusive or exclusive of tax.

The previous code that made use of the Price entity looked something like this

The code in the second example is much easier to read and has no knowledge of the fact that a price entity return from the price repository could be inclusive or exclusive of tax. The calling code is also a lot easier to unit test as there is now only a single route through it.